The invention relates to apparatus including at least two parts that are mounted in aligned and fixed relationship and then joined together. The apparatus includes means for readily aligning the two parts and mounting them in a preselected joined relationship. More particularly, the invention relates to apparatus that includes a first part having a plurality of spaced apertures that are adapted to have bolts or other holding means inserted through them, in combination with a second part provided with spaced, threaded holes for receiving such bolts so that the bolts or other holding means can be used to clamp the first part to the second part when they are aligned and mounted in fixed relationship according to the invention. In an alternative embodiment, a rabbet fit is provided between the first and second parts in place of one of the apertures and associated bolts in said plurality of spaced apertures. The disclosed embodiment also includes a method for practicing the invention to mount a first and second part of such an apparatus in a predetermined aligned and fixed relationship.
A great variety of coupling methods and systems are well known for joining two components of an assembly in a desired fixed and aligned relationship. In general, such known prior art techniques and apparatus can be divided into three separate categories. One such category is exemplified by U.S. Pat. No. 3,493,249-Conrad, Jr., et al, wherein concentric bushings are often used in combination with joining bolts or other holding means for providing a small clearance fit between the bolt shaft and the bushings, while at the same time reducing the size of clearance fit between the bushings and the walls of apertures through parts that are secured together by the bolts. A second category of prior art technology for securing two parts in aligned and fixed relationship is shown, for example, in either U.S. Pat. Nos. 2,528,343-Davis or 3,065,000-Stanton. As disclosed in those patents, one of a pair of parts that is to be joined together is provided with a plurality of spaced apertures that each have diameters sized to provide a relatively close clearance fit for bolts or other holding means adapted to be inserted through the apertures. A second part to be joined by such bolts to the first part is provided with a plurality of spaced apertures that are substantially larger, along one of their respective diameters, than the largest diameter of a matched aperture in the first part. With such system, the bolts or holding means can be inserted through the relatively small-diameter apertures in the first part, then fitted loosely through the apertures in the second part, after which the second part can be moved relative to the first part in a direction so that movement of the second part parallel to the relatively long axis of the apertures is achieved thereby to obtain a desired snug fit between the bolts and one end, or side of the elongated apertures in the second part. A common modification of the technology in this second category is shown in U.S. Pat. No. 4,035,093-Redshaw which discloses an apparatus including two plate members that are joined together. Each of the plate members is provided with a plurality of spaced apertures having major longitudinal axes and minor transverse axes. The apertures in the first plate are arranged to overlap the respective apertures in the second plate in approximately a perpendicular relationship. With this type of apparatus, bolts can be readily positioned between the matched pairs of apertures at the junction of their axes and the plates can be secured in a relatively wide range of different positions, as determined by the linear extent of the two sets of elongated apertures.
Finally, the various types of prior art mounting end aligning techniques known to the applicant include aligning and joining methods that require the use of a plurality of precisely machined, low tolerance clearance, aligning and mounting apertures and associated bolts and bolt receiving holes arranged respectively in precisely aligned relationship in two members of an apparatus that are to be joined together. An example of such a relatively expensive to implement, precision machined mounting method is shown in U.S. Pat. No. 3,257,720-Siler where, as disclosed in that patent, two parts are joined together by precisely machining a single locator hole in one of the parts to receive therein a holding bolt. Other threaded bolt holes are positioned on the first member at spaced points that are each located within a predetermined tolerance at selected positions on the first member. In similar fashion, a single precisely machined locator aperture is formed in the second member to be aligned exactly with the locator hole in the first member. In addition, a plurality of other apertures are provided in the second member, each located within a predetermined tolerance relative to the position of the first locator hole in the second member so that the respective apertures in the second member are in alignment with matching holes in the first member, within the range of tolerance buildup afforded by the tolerance clearances between the first locator hole, the holding bolt and the associated aperture, and including the tolerance clearance between any given matched hole in the first member and a juxtaposed aperture in the second member.
Although the various aligning and joining methods known in the prior art are suitable for certain applications, each of them is limited in at least one of two important respects. Generally speaking, such prior art methods either provide relatively inaccurate alignment between the parts that are joined together, as is indicated by the first two categories of prior art patents discussed above, or alternatively, in those cases where better precision alignment is obtained, relatively expensive precision machining is required to practice the method and careful, time-consuming assembly procedures are required to achieve the desired accurate alignment of two joined parts, as is explained for example in the type of method disclosed in the Siler patent discussed above.
It would be very advantageous in many manufacturing operations to provide aligning and joining apparatus and techniques whereby two parts of an assembly could be quickly and efficiently joined together in precise alignment at a relatively low cost. One application in which such an improved apparatus and method is particularly desirable is in the aligning and mounting of annular air baffles in closely spaced concentric relationship around the rotor of electric motors or generators. In order to illustrate one preferred embodiment of the present invention the disclosure of the invention presented herein will be made in connection with its application to such an air baffle mounting and aligning apparatus and method.